/*
 * Copyright 2002-2010 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using System.Globalization;
using System.Web;
using Spring.Util;

namespace Spring.Globalization.Resolvers;

/// <summary>
/// Default culture resolver for web applications. Contains some common utility methods for web culture resolvers.
/// </summary>
/// <author>Aleksandar Seovic</author>
public class DefaultWebCultureResolver : DefaultCultureResolver
{
    /// <summary>
    /// Returns default culture. If <see cref="DefaultCultureResolver.DefaultCulture"/> property is not set,
    /// it tries to get culture from the request headers
    /// and falls back to a current thread's culture if no headers are available.
    /// </summary>
    /// <returns>Default culture to use.</returns>
    protected override CultureInfo GetDefaultLocale()
    {
        if (DefaultCulture != null)
        {
            return base.DefaultCulture;
        }

        CultureInfo culture = GetCulture(GetRequestLanguage());
        if (culture != null)
        {
            return culture;
        }

        return Thread.CurrentThread.CurrentUICulture;
    }

    /// <summary>
    /// Extracts the users favorite language from "accept-language" header of the current request.
    /// </summary>
    /// <returns>a language string if any or <c>null</c>, if no languages have been sent with the request</returns>
    protected virtual string GetRequestLanguage()
    {
        HttpContext context = HttpContext.Current;
        if (context != null && context.Request != null && ArrayUtils.HasLength(context.Request.UserLanguages))
        {
            return context.Request.UserLanguages[0];
        }

        return null;
    }

    /// <summary>
    /// Resolves a culture by name.
    /// </summary>
    /// <param name="cultureName">the name of the culture to get</param>
    /// <returns>a (possible neutral!) <see cref="CultureInfo"/> or <c>null</c>, if culture could not be resolved</returns>
    public CultureInfo GetCulture(string cultureName)
    {
        try { return new CultureInfo(cultureName.Split(';')[0]); }
        catch { }

        return null;
    }

    /// <summary>
    /// Resolves the culture from the context.
    /// </summary>
    /// <returns>Culture that should be used to render view.</returns>
    public override CultureInfo ResolveCulture()
    {
        return GetDefaultLocale();
    }

    /// <summary>
    /// Not supported for this implementation.
    /// </summary>
    /// <param name="culture">The new culture or <code>null</code> to clear the culture.</param>
    public override void SetCulture(CultureInfo culture)
    {
        throw new NotSupportedException("Cannot change a default culture in a web application - use a different culture resolution strategy.");
    }
}